The drive to miniaturization has led to the development of chip-scale or nearly chip-scale semiconductor devices. One variety of such devices includes a can-shaped connector which receives a semiconductor die in its interior and connects to an electrode of the die by a layer of conductive material such as solder or conductive epoxy. The can-shaped connector includes a wall portion which skirts around the die. The wall is closely spaced from the peripheral edges of the die and its electrodes. When such a device is soldered to a board using fluxed solder pastes residual flux is deposited around the soldered joints. When fluxes other than those marketed as “no clean” products are used for this purpose it is necessary to wash these residuals from under the device to prevent the device from suffering from the formation of corrosion or electrical breakdown.
FIGS. 1A-1B and 2A-2B show examples of known semiconductor devices in which a MOSFET silicon die 10, having a drain electrode 9 on its top surface and source electrode 14 and gate electrode (not shown) on its bottom surface, is housed in a conductive metal can 11. Thus, drain electrode 9 is secured, as by soldering or by a conductive adhesive to the interior surface of can 11. The rim 12 of can 11 is spaced from the periphery of die 10. Optionally, an insulation ring 13 may be provided between rim 12 and can 11. The bottom surface of source electrode 14 may be coplanar or slightly sub-flush with respect to the bottom of flange 15 of rim 12. Solder flux residue must be washed out when the package is soldered down to conductive traces on board 17. A shallow gap 16 (See FIG. 2B) between the rim 12 of the can and the board limits the ability for the cleaning medium to freely flow under the device. Therefore, adequate washing under the device cannot be easily achieved. Also, the close spacing between source electrode 14 and the interior of rim 12 may hinder the washing of the flux residue and may reduce the voltage which can be applied to the package.
Therefore, a semiconductor device is desired which allows for the easier washing of the flux residue and higher voltage applications.